Compression test question
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Joined: Oct 2013
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From: NY
Compression test question
76 FXE 74"
Maybe a dumb question but I don't know the answer:
Can I do a compression test with the pipes, carb & intake off the bike?
I've been tinkering with this bike after inheriting it recently. It's been parked for 23 yrs, and I'm hopeful but not positive it ran when parked. My aunt who gave it to me "thinks" it did.
Over the past month I've stripped the bike to do small things like a new harness, bearings, oil lines, paint, and basically a good run-through of everything but the eng/tran. Now that I'm almost ready to put stuff back together, I figured I should at least check the compression first.
That being said, with the pipes, carb, & intake still off I put the tester in each cylinder and pumped the kicker a few times by hand. Both cylinders read approx 25 psi.
My heart sank, but I'm hoping I did something wrong. Any help is appreciated. Thanks
Maybe a dumb question but I don't know the answer:
Can I do a compression test with the pipes, carb & intake off the bike?
I've been tinkering with this bike after inheriting it recently. It's been parked for 23 yrs, and I'm hopeful but not positive it ran when parked. My aunt who gave it to me "thinks" it did.
Over the past month I've stripped the bike to do small things like a new harness, bearings, oil lines, paint, and basically a good run-through of everything but the eng/tran. Now that I'm almost ready to put stuff back together, I figured I should at least check the compression first.
That being said, with the pipes, carb, & intake still off I put the tester in each cylinder and pumped the kicker a few times by hand. Both cylinders read approx 25 psi.
My heart sank, but I'm hoping I did something wrong. Any help is appreciated. Thanks
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From: la la land jerzey
If you dont ask questions well thats dumb
sure you can do compression test with all that stuff off - BUT turning it by hand is way to slow to get real numbers --But the fact that they were both the same is a good thing
a motor that has been sitting for years on end usually has very little compression like your getting -- you should / could put all needed back on and fire it up before you get going any more on the project === just to be sure no other issues are hiding in it -- jz
sure you can do compression test with all that stuff off - BUT turning it by hand is way to slow to get real numbers --But the fact that they were both the same is a good thing
a motor that has been sitting for years on end usually has very little compression like your getting -- you should / could put all needed back on and fire it up before you get going any more on the project === just to be sure no other issues are hiding in it -- jz
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Joined: Mar 2007
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From: Patten,Maine
You should really find a way to give it some good kicks and you just might be better off doing a leakdown test in your situation...FWIW...A leakdown test has you get the cylinder to a spot where the valves are closed and fill the cylinder with compressed air through a fitting that goes into the sparkplug hole...if you have bad rings you will see the pressure drop and may hear it leaking into the lower end (remove your timing plug) or if your valves aren't seating you may hear it leaking through the manifold or the exhaust ports...pretty simple if you can get the fittings,which you have on your compression tester ...
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Joined: Mar 2006
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If it's been sitting 23yrs then things can get a little rusty and sticky, get some Marvel Mystery oil and squirt some in each spark plug hole. Turn over a few times and let it set overnight. This will help lube pistons and rings.
You should try to get the elec start working for the compression test as it will spin the engine faster than you can kick it. If not then kick 5-6 times repeatedly on each cyl.
This will give you a better reading on condition of the rings. If no increase in pressure then the valves may be sticking or damaged.
You should try to get the elec start working for the compression test as it will spin the engine faster than you can kick it. If not then kick 5-6 times repeatedly on each cyl.
This will give you a better reading on condition of the rings. If no increase in pressure then the valves may be sticking or damaged.
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Joined: Oct 2013
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From: NY
Update:
I'm a little farther along in the project. Got it wired up enough to test the starter, which works thankfully, and got a reading of 119 front cylinder, 120 rear. That's awesome, I feel much better now! Next will be the leakdown test.
I'll be firing her up in a couple days, time permitting.
Thanks so much for your help!
I'm a little farther along in the project. Got it wired up enough to test the starter, which works thankfully, and got a reading of 119 front cylinder, 120 rear. That's awesome, I feel much better now! Next will be the leakdown test.
I'll be firing her up in a couple days, time permitting.
Thanks so much for your help!
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